1. Field of the Invention
The invention relates to a spray gun.
2. Prior Art
When working with a spray gun, it is extremely important to adjust the spraying pressure to produce optimum atomization for optimum work results at a good working speed and high application efficiency. A spraying pressure that is too low can lead, e.g., to color changes in the base coating, to an increase in the orange-peel structure in clear coatings and plain lacquer, and to a reduction of working speed and possibly the stream width. On the other hand, a spraying pressure that is too high can cause too great an atomization of the spray material and thus to greater losses and undesired stress on the work environment. Also, during the spraying process, the available pressure should be monitored to recognize possible pressure drops due to additional loads on the compressed-air network or pressure increases due to the activation of resources.
Frequently a pressure-regulating valve with a manometer is connected to the input of the spray gun in order to adjust and monitor the spraying pressure. The pressure, which can be adjusted by means of an adjustment knob on the pressure-regulating valve, can be read on the manometer. However, this pressure-regulating valve with manometer at the air inlet of the paint spray gun leads to a lengthening of the spray gun, which produces poorer handling. In addition, due to the rerouted inner channels, the manometer or the pressure-regulating valve produces a pressure drop. Also, the pressure-regulating valve, which is usually screwed on, must be disassembled for cleaning the spray gun in washing devices or cleaning tanks, because the display accuracy of the manometer can be negatively affected by solvent or coating or paint residue entering the instrument. Therefore, the pressure-regulating valve with the manometer must be removed for each cleaning process, which is associated with considerable work effort.
Paint spray guns are also already known, which have a connection on the bottom side of the handle for coupling to a conventional manometer. The manometers that are regularly used usually have a semicircular or spiral-shaped, curved steel tube spring as the pressure sensor, whose change in shape caused by the pressure is displayed by a pointer on a corresponding instrumental dial. The steel tube spring and the display device are mounted in a special housing. However, for this configuration, the handling of the spray gun is also negatively affected by the coupled manometer. In addition, the manometer must be removed for cleaning the paint spray gun, so that relatively expensive coupling or connecting systems are required for connecting the manometer to the spray gun.
It has also already been proposed to attach a conventional manometer to the side of the gun body. Such a spray gun also exhibits worse handling due to the manometer, which projects outward to one side. In addition, such a spray gun must be handled with extreme care so that the manometer attached to one side is not damaged when the spray gun is laid down.